From 726c281cdd3824fcfdde34fe8d01f95416f7808c Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Tue, 7 May 2019 16:01:24 +0200
Subject: Clean up some of the SubExpr type-changing methods

---
 dhall_syntax/src/core.rs    | 40 ++++++---------------
 dhall_syntax/src/visitor.rs | 84 +++------------------------------------------
 2 files changed, 16 insertions(+), 108 deletions(-)

(limited to 'dhall_syntax')

diff --git a/dhall_syntax/src/core.rs b/dhall_syntax/src/core.rs
index 7cdda64..2b76b9a 100644
--- a/dhall_syntax/src/core.rs
+++ b/dhall_syntax/src/core.rs
@@ -343,15 +343,11 @@ impl<N, E> Expr<N, E> {
     {
         trivial_result(self.traverse_embed(|x| Ok(map_embed(x))))
     }
+}
 
-    pub fn squash_embed<E2>(
-        &self,
-        f: impl FnMut(&E) -> SubExpr<N, E2>,
-    ) -> SubExpr<N, E2>
-    where
-        N: Clone,
-    {
-        trivial_result(self.visit(&mut visitor::SquashEmbedVisitor(f)))
+impl Expr<X, X> {
+    pub fn absurd<N, E>(&self) -> Expr<N, E> {
+        self.visit(&mut visitor::AbsurdVisitor)
     }
 }
 
@@ -361,12 +357,6 @@ impl<E: Clone> Expr<X, E> {
     }
 }
 
-impl<N: Clone> Expr<N, X> {
-    pub fn embed_absurd<E>(&self) -> Expr<N, E> {
-        self.visit(&mut visitor::EmbedAbsurdVisitor)
-    }
-}
-
 impl<N, E> SubExpr<N, E> {
     pub fn as_ref(&self) -> &Expr<N, E> {
         &self.0.as_ref().0
@@ -380,17 +370,6 @@ impl<N, E> SubExpr<N, E> {
         SubExpr(Rc::new((x, None)))
     }
 
-    pub fn unnote(&self) -> SubExpr<X, E>
-    where
-        E: Clone,
-    {
-        SubExpr::from_expr_no_note(
-            self.as_ref().visit(&mut visitor::UnNoteVisitor),
-        )
-    }
-}
-
-impl<N: Clone, E> SubExpr<N, E> {
     pub fn rewrap<E2>(&self, x: Expr<N, E2>) -> SubExpr<N, E2>
     where
         N: Clone,
@@ -422,7 +401,10 @@ impl<N: Clone, E> SubExpr<N, E> {
         &'a self,
         map_expr: impl FnMut(&'a Self) -> Self,
         map_under_binder: impl FnMut(&'a Label, &'a Self) -> Self,
-    ) -> Self {
+    ) -> Self
+    where
+        N: Clone,
+    {
         match self.as_ref() {
             ExprF::Embed(_) => SubExpr::clone(self),
             // This calls ExprF::map_ref
@@ -436,9 +418,9 @@ impl<N: Clone, E> SubExpr<N, E> {
     }
 }
 
-impl<N: Clone> SubExpr<N, X> {
-    pub fn embed_absurd<T>(&self) -> SubExpr<N, T> {
-        self.rewrap(self.as_ref().embed_absurd())
+impl SubExpr<X, X> {
+    pub fn absurd<N: Clone, T>(&self) -> SubExpr<N, T> {
+        SubExpr::from_expr_no_note(self.as_ref().absurd())
     }
 }
 
diff --git a/dhall_syntax/src/visitor.rs b/dhall_syntax/src/visitor.rs
index 7fdf217..20bfc72 100644
--- a/dhall_syntax/src/visitor.rs
+++ b/dhall_syntax/src/visitor.rs
@@ -421,78 +421,6 @@ where
     }
 }
 
-pub struct SquashEmbedVisitor<F1>(pub F1);
-
-impl<'a, 'b, N, E1, E2, F1>
-    ExprFVeryGenericVisitor<'a, SubExpr<N, E2>, SubExpr<N, E1>, Label, E1>
-    for &'b mut SquashEmbedVisitor<F1>
-where
-    N: Clone + 'a,
-    F1: FnMut(&E1) -> SubExpr<N, E2>,
-{
-    type Error = X;
-    type SE2 = SubExpr<N, E2>;
-    type L2 = Label;
-    type E2 = E2;
-
-    fn visit_subexpr(
-        &mut self,
-        subexpr: &'a SubExpr<N, E1>,
-    ) -> Result<Self::SE2, Self::Error> {
-        Ok(subexpr.as_ref().visit(&mut **self)?)
-    }
-
-    fn visit_label(
-        &mut self,
-        label: &'a Label,
-    ) -> Result<Self::L2, Self::Error> {
-        Ok(Label::clone(label))
-    }
-
-    fn visit_binder(
-        mut self,
-        label: &'a Label,
-        subexpr: &'a SubExpr<N, E1>,
-    ) -> Result<(Self::L2, Self::SE2), Self::Error> {
-        Ok((self.visit_label(label)?, self.visit_subexpr(subexpr)?))
-    }
-
-    fn visit_embed_squash(
-        self,
-        embed: &'a E1,
-    ) -> Result<SubExpr<N, E2>, Self::Error> {
-        Ok((self.0)(embed))
-    }
-
-    // Called with the result of the map, in the non-embed case.
-    // Useful to change the result type, and/or avoid some loss of info
-    fn visit_resulting_exprf(
-        result: ExprF<Self::SE2, Self::L2, Self::E2>,
-    ) -> Result<SubExpr<N, E2>, Self::Error> {
-        // TODO: don't lose note
-        Ok(SubExpr::from_expr_no_note(result))
-    }
-}
-
-pub struct UnNoteVisitor;
-
-impl<'a, 'b, N, E>
-    ExprFInFallibleVisitor<'a, SubExpr<N, E>, SubExpr<X, E>, Label, Label, E, E>
-    for &'b mut UnNoteVisitor
-where
-    E: Clone + 'a,
-{
-    fn visit_subexpr(&mut self, subexpr: &'a SubExpr<N, E>) -> SubExpr<X, E> {
-        SubExpr::from_expr_no_note(subexpr.as_ref().visit(&mut **self))
-    }
-    fn visit_embed(self, embed: &'a E) -> E {
-        E::clone(embed)
-    }
-    fn visit_label(&mut self, label: &'a Label) -> Label {
-        Label::clone(label)
-    }
-}
-
 pub struct NoteAbsurdVisitor;
 
 impl<'a, 'b, N, E>
@@ -512,16 +440,14 @@ where
     }
 }
 
-pub struct EmbedAbsurdVisitor;
+pub struct AbsurdVisitor;
 
 impl<'a, 'b, N, E>
-    ExprFInFallibleVisitor<'a, SubExpr<N, X>, SubExpr<N, E>, Label, Label, X, E>
-    for &'b mut EmbedAbsurdVisitor
-where
-    N: Clone + 'a,
+    ExprFInFallibleVisitor<'a, SubExpr<X, X>, SubExpr<N, E>, Label, Label, X, E>
+    for &'b mut AbsurdVisitor
 {
-    fn visit_subexpr(&mut self, subexpr: &'a SubExpr<N, X>) -> SubExpr<N, E> {
-        subexpr.rewrap(subexpr.as_ref().visit(&mut **self))
+    fn visit_subexpr(&mut self, subexpr: &'a SubExpr<X, X>) -> SubExpr<N, E> {
+        SubExpr::from_expr_no_note(subexpr.as_ref().visit(&mut **self))
     }
     fn visit_embed(self, embed: &'a X) -> E {
         match *embed {}
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